Figure 3.

Example mass spectra for calcined zeolite ZSM‐5 and ZSM‐5 after the methanol‐to‐hydrocarbons (MTH) reaction using both normal methanol (¹²CH₃OH) and ¹³C isotopically labelled methanol (¹³CH₃OH), with the top traces in log sale and the bottom in linear scale for counts. a) Full relevant mass scale showing the abundance of peaks observed. b) Region showing the presence of ¹²C and ¹³C in both reacted samples, with an abundance of ¹³C from the labelled reaction. c) The peak near 28 Da contains contributions from ²⁸Si and then after the MTH reaction a clear shift due to ¹²CO is observed. d) The peak near 29 Da is from ²⁹Si and then after reaction predominately ¹³CO as well as a contribution from ¹²COH. Note the CO peak was determined to contain 80 % of all carbon making its quantification vital. Samples are from Refs. 64, 70.